Antimicrobial, antioxidant, anti-inflammatory, and cytotoxic activities of Cordyceps militaris spent substrate

Abstract

Cordyceps militaris is a medicinal mushroom and has been extensively used as a traditional medicine in East Asia. After the chrysalis seeds are matured and harvested, the spent substrate of C. militaris still contains active ingredients but is usually discarded as waste. This study aimed to determine the antioxidant and anti-inflammatory activities of C. militaris spent substrate extract and its inhibitory activity on the Malassezia commensal yeasts that can cause dandruff and seborrheic dermatitis. Active substances in the spent substrate of C. militaris were extracted using a hot water extraction method and were used for the determination of antioxidant activity by measuring their ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radicals, hydrogen peroxide, and superoxide anions. The ability to inhibit Malassezia was analyzed using the broth microdilution method, and the reparative effect on oxidative damage in HaCaT cells was measured using in vitro cell analysis. Respiratory burst evaluation was used to determine the anti-inflammatory capacity of extracts. Analysis of the Malassezia-inhibiting activity of the extracts showed that the minimum inhibitory concentration was 6.25 mg/mL. The half maximal inhibitory concentration (IC50) values of DPPH, O2-, H2O2 and OH- were 3.845 mg/mL, 2.673 mg/mL, 0.037 mg/mL and 0.046 mg/mL, respectively. In the concentration range of 2 to 50%, the extract was non-toxic to cells and was able to protect HaCaT cells from H2O2 damage. When the volume fraction of the extract was 20.96%, its anti-inflammatory ability reached 50%. These results demonstrated that the extract may be a safe and efficacious source for pharmaceutical or cosmetic applications, with Malassezia-inhibiting, antioxidant and anti-inflammatory activities.